How to change the color of the writing area?

I want to distinguish the writing area from non writing area. Kindly see the attachment.


How can I do this?

Here’s how I achieved this (there might be better ways, I’m quite a newbie):

Go to .obsidian/snippets and create a textfile (i.e. editor.css) with the content:
.CodeMirror-lines {
background-color: brown;
}
Save it and switch on in settings ‘appearance’ / ‘css snippets’ the snippet (‘editor.css’) you just created.
Replace ‘brown’ in the file with the color desired.

Thank you so much you. I also managed to change the color in preview mode using yours has a reference.

.CodeMirror-lines {
 background-color: #faf5f0;
}
.markdown-preview-sizer.markdown-preview-section {
 background-color: #faf5f0;
}

.markdown-preview-view.is-readable-line-width.allow-fold-headings.allow-fold-lists {
 background-color: #D3D3D3;
}
.markdown-source-view.mod-cm5.is-readable-line-width {
 background-color: #D3D3D3;
}